1. Field of the Invention
The present invention relates to the field of microprocessor-based computer systems, and relates more particularly to modification of the operation of a keyboard to perform operations normally associated with a mouse pointing device
2. Description of the Related Art
Over the past several years, a number of peripheral devices which perform specialized operations have been designed and implemented in order to enhance the operation of microprocessor-based computer systems. Such peripheral devices may, for example, facilitate user interaction with the system. One example of such a peripheral device is the "mouse" pointer. This device allows a user to quickly and easily point to any location on a computer terminal display screen. The mouse pointers are particularly useful in computers which employ "window" displays, pull-down menus and/or icons. This is because the mouse can be used to point to a given window or icon and to activate the function designated by the display window or icon. Hence, mouse pointers have become especially popular over the past several years, and have gained wide acceptance within the computer industry.
A conventional mouse pointer comprises an external, hand-operable device which detects motion in reference to a flat surface. For example, a conventional mouse device may include a partially encapsulated rubber ball which is exposed on one surface, and is in continuous contact with cylindrical rollers inside the mouse. When the exposed surface of the ball is placed in contact with a flat surface and is moved across this surface, the ball rotates, and the frictional force between the rubber ball and the rollers inside the mouse causes the rollers to move. The movement of these rollers may subsequently be detected and converted into electrical signals corresponding to the vertical and horizontal motion of the mouse pointer. The signals thus generated are converted into digital information which is used to determine the speed and direction of the pointer on the screen. Typically, conventional mouse devices also include one or more buttons which may be used to select an option or activate a given function.
Although conventional mouse devices have proven very useful under normal circumstances, the use of such devices may be impaired under conditions where no flat surface is available, or when a significant amount of vibration or movement is present. Such conditions often prevail during air or automobile travel, and generally in many circumstances where one uses a lap-top or notebook computer.
Due to the aforementioned problems, it is desirable to provide a device which allows a user to perform mouse-like operations without the necessity of a flat, steady surface. Furthermore, it is desirable that such a device be implemented so that it may function in accordance with existing computer systems.